git.openwrt.org Git - openwrt/staging/jow.git/blob

   1 From c0863c6da514311d3db381bcc1be6e0435d9b8c9 Mon Sep 17 00:00:00 2001
   2 From: Naushir Patuck <naush@raspberrypi.com>
   3 Date: Fri, 5 Mar 2021 15:40:45 +0000
   4 Subject: [PATCH] media: bcm2835-unicam: Fix bug in buffer swapping
   5  logic
   6
   7 If multiple sets of interrupts occur simultaneously, it may be unsafe
   8 to swap buffers, as the hardware may already be re-using the current
   9 buffers. In such cases, avoid swapping buffers, and wait for the next
  10 opportunity at the Frame End interrupt to signal completion.
  11
  12 Additionally, check the packet compare status when watching for frame
  13 end for buffers swaps, as this could also signify a frame end event.
  14
  15 Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
  16 ---
  17  .../media/platform/bcm2835/bcm2835-unicam.c   | 21 ++++++++++++++++---
  18  1 file changed, 18 insertions(+), 3 deletions(-)
  19
  20 --- a/drivers/media/platform/bcm2835/bcm2835-unicam.c
  21 +++ b/drivers/media/platform/bcm2835/bcm2835-unicam.c
  22 @@ -800,6 +800,7 @@ static irqreturn_t unicam_isr(int irq, v
  23         unsigned int sequence = unicam->sequence;
  24         unsigned int i;
  25         u32 ista, sta;
  26 +       bool fe;
  27         u64 ts;
  28
  29         sta = reg_read(unicam, UNICAM_STA);
  30 @@ -817,12 +818,18 @@ static irqreturn_t unicam_isr(int irq, v
  31                 return IRQ_HANDLED;
  32
  33         /*
  34 +        * Look for either the Frame End interrupt or the Packet Capture status
  35 +        * to signal a frame end.
  36 +        */
  37 +       fe = (ista & UNICAM_FEI || sta & UNICAM_PI0);
  38 +
  39 +       /*
  40          * We must run the frame end handler first. If we have a valid next_frm
  41          * and we get a simultaneout FE + FS interrupt, running the FS handler
  42          * first would null out the next_frm ptr and we would have lost the
  43          * buffer forever.
  44          */
  45 -       if (ista & UNICAM_FEI || sta & UNICAM_PI0) {
  46 +       if (fe) {
  47                 /*
  48                  * Ensure we have swapped buffers already as we can't
  49                  * stop the peripheral. If no buffer is available, use a
  50 @@ -833,7 +840,15 @@ static irqreturn_t unicam_isr(int irq, v
  51                         if (!unicam->node[i].streaming)
  52                                 continue;
  53
  54 -                       if (unicam->node[i].cur_frm)
  55 +                       /*
  56 +                        * If cur_frm == next_frm, it means we have not had
  57 +                        * a chance to swap buffers, likely due to having
  58 +                        * multiple interrupts occurring simultaneously (like FE
  59 +                        * + FS + LS). In this case, we cannot signal the buffer
  60 +                        * as complete, as the HW will reuse that buffer.
  61 +                        */
  62 +                       if (unicam->node[i].cur_frm &&
  63 +                           unicam->node[i].cur_frm != unicam->node[i].next_frm)
  64                                 unicam_process_buffer_complete(&unicam->node[i],
  65                                                                sequence);
  66                         unicam->node[i].cur_frm = unicam->node[i].next_frm;
  67 @@ -870,7 +885,7 @@ static irqreturn_t unicam_isr(int irq, v
  68          * where the HW does not actually swap it if the new frame has
  69          * already started.
  70          */
  71 -       if (ista & (UNICAM_FSI | UNICAM_LCI) && !(ista & UNICAM_FEI)) {
  72 +       if (ista & (UNICAM_FSI | UNICAM_LCI) && !fe) {
  73                 for (i = 0; i < ARRAY_SIZE(unicam->node); i++) {
  74                         if (!unicam->node[i].streaming)
  75                                 continue;